Particle filter assembly

ABSTRACT

A particle filter assembly adapted to be mounted in an exhaust gas stream of an internal combustion engine. The particle filter assembly includes a wire mesh filter or sinter metal filter having a mesh size sufficiently small to prevent the passage of carbonaceous particles above a predetermined size through the mesh. The filter is positioned in series with the exhaust gas stream from the engine. A source of electrical power is electrically connected to the filter to heat the filter to a temperature sufficient to oxidize the carbonaceous material in the filter to carbon dioxide.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to a particle filter assembly adapted to be mounted in series with the exhaust gas stream from an internal combustion engine.

II. Description of Related Art

In view of increasingly stringent governmental regulations, off-road machinery, such as trains, marine vessels and machinery, large mining vehicles and the like, need to be fitted with exhaust treating devices to reduce the amount of pollutants exhausted to the atmosphere. Such off-road devices are typically powered by diesel engines which emit solid carbonaceous particles.

In such off-road vehicles, the internal combustion engine has an output shaft mechanically connected to one or more electric generators. The output from the electric generators, in turn, is electrically connected to one or more electric engines which propel the train.

In many operating conditions, such as when a train is powered along a level path or an up slope, additional fuel may be necessary for the internal combustion engine in order to provide sufficient electrical output from the generators to power not only the electric motors which propel the train, but also any other electric systems in the train. Conversely, in other operating conditions, such as a coast down condition when the train is traveling along a down slope, the electrical generators on the train generate excess electrical power that is, for the most part, unused and therefore wasted. These conditions of excess electrical power are known as the boost status for the train or other off-road machinery.

SUMMARY OF THE PRESENT INVENTION

The present invention provides a particle filter for use with the exhaust gas stream from an internal combustion engine which utilizes the excess electrical energy generated during the boost status of the machinery to clean or regenerate the particle filter by oxidizing the carbonaceous particles contained within the filter.

In brief, the particle filter assembly of the present invention comprises a wire mesh filter or sinter metal filter having a mesh size sufficiently small to prevent the passage of carbonaceous particles above a predetermined size through the mesh. The filter is positioned in series with the exhaust gas stream from the internal combustion engine.

A source of electrical power which includes an electrical generator is mechanically coupled with the mechanical output from the internal combustion engine. Consequently, rotation of the engine rotatably drives the generator to produce electric power.

A control circuit electrically connects the electrical power source to the filter at spaced time intervals during the boost status for the vehicle and for a sufficient time during each connection of electric power to the filter to heat the filter to a temperature sufficient to oxidize the carbonaceous material in the mesh to carbon dioxide. The harmless carbon dioxide is then exhausted by the exhaust system to the atmosphere.

Consequently, the present invention effectively periodically regenerates and cleans the filter in the exhaust gas stream from the engine during boost status for the off-road machinery without the necessity for the engine to produce excess electrical power to do so. Rather, since only the excess electrical power during the boost status of the engine is used to regenerate the filter, the regeneration and cleaning of the filter is achieved in a highly energy-efficient manner.

A method for regenerating or cleaning the filter is also disclosed.

BRIEF DESCRIPTION OF THE DRAWING

A better understanding of the present invention will be had upon reference to the following detailed description when read in conjunction with the accompanying drawing, wherein like reference characters refer to lice parts throughout the several views, and in which:

FIG. 1 is a block diagrammatic view illustrating an embodiment of the present invention; and

FIG. 2 is a plan view illustrating a portion of the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION

With reference first to FIG. 1, an off-road machine or vehicle 10, such as a train engine car, marine application, large mining vehicles and the like, is diagrammatically illustrated. The vehicle 10 includes an internal combustion engine 12 that is typically powered by diesel or other relatively low cost fuel. The internal combustion engine 12 produces an exhaust gas stream through an exhaust system 14 which includes one or more exhaust pipes.

The internal combustion engine 12 includes an output shaft 16 which is rotatably driven by the internal combustion engine 12 during operation of the engine 12. The generator in the conventional fashion generates electric power at its output 18.

The output 18 from the generator 20 is electrically connected to one or more electric motors 22 which power the drive system (not shown) for the vehicle 10. Consequently, when the load increases and additional power is required by the electric motors 22 and/or other electric systems on the vehicle, additional fuel is typically supplied to the engine 12 which increases the power output from the engine 12. Conversely, under other operating conditions, such as when the vehicle 10 is in a coast down condition and traveling on a down slope and is in a boost status, the vehicle electric motor 22 drives the generator 20 which then produces excess electrical power. In the past this additional electric power, for the most part, was unused and therefore wasted.

With reference now to FIGS. 1 and 2, a particle filter assembly 30 is positioned in series with the exhaust system 14 of the internal combustion engine 12. Consequently, the exhaust gas stream from the internal combustion engine 12 passes through the filter assembly 30.

As best shown in FIG. 2, the particle filter assembly 30 includes a wire mesh or sinter metal filter 32 (hereinafter collectively referred to as a filter) having a mesh size sufficiently small to prevent the passage of carbonaceous particles above a predetermined size through the wire mesh. Consequently, the filter 32 entraps the carbonaceous particles in the smoke from the internal combustion engine 12 that would otherwise be expelled to the atmosphere.

The filter 32 may be constructed of any suitable material that conducts electricity. For example, stainless steel, copper, and other metals may be used to form the filter 32.

After a period of time of operation of the internal combustion engine 12, the filter assembly 30 must be regenerated or cleaned of the carbonaceous particles 34 in order to prevent clogging of the filter assembly 30. Otherwise, such clogging would impede the exhaust gas stream gas flow from the engine 12.

In order to regenerate or clean the filter assembly 30 at spaced time intervals and preferably during boost status of the vehicle 10, a control circuit 38, which may be microprocessor based, is electrically connected between the generator output 18 and the wire mesh 32. During the boost status of the vehicle 10, i.e. when the generator 20 generates excess electrical power, the control circuit 38 electrically connects the output from the power source to the filter 32 which, of course, causes heating of the filter 32 due to the passage of electrical current and the electrical resistance of the material forming the filter 32. The control circuit 38, operating under either open loop or closed loop control, controls the amount of electrical power supplied to the mesh to heat the filter 32 to a temperature sufficient to oxidize the carbonaceous material 34 in the filter 32 to carbon dioxide. The carbon dioxide passes out through an outlet 40 (FIG. 1) from the exhaust system 14 harmlessly into the atmosphere. Furthermore, in doing so, the carbonaceous particles 34 are removed from the filter 32 thus regenerating or cleaning the particle filter assembly 30.

Although the control circuit 38 may completely regenerate the wire mesh 32 during each regeneration cycle, alternatively the control circuit 38, which may be microprocessor based, may only partly regenerate the wire mesh 32 based on an estimation of whether the regeneration would negatively influence the overall efficiency of the operation of the wire mesh 32. Such an estimation of the overall efficiency could, for example, utilize the exhaust gas pressure across the wire mesh 32 and the effect on fuel consumption to in turn control the degree of regeneration. Additionally, the control circuit 38 may selectively electrically energize different parts of the wire mesh 32 so that the different parts of the wire mesh 32 may be sequentially regenerated during different regeneration cycles.

Although the present invention has been described for use with a train, it will be understood that the filter assembly 30 may be used with other types of internal combustion engines without deviation from the spirit or scope of the invention. Such other types of internal combustion engines include, for example, marine applications, large mining vehicles and the like.

A primary advantage of the present invention is that, since the filter assembly 30 is regenerated or cleaned using only excess electrical power which would otherwise be unused and thus wasted, the present invention achieves cleaning of the filter assembly 30 without the consumption of extra fuel and thus is highly energy efficient. However, the electrical power for the regeneration of the filter 32 may alternatively be obtained, in whole or in part, from batteries or other sources of electrical energy on the vehicle.

The present invention also includes a method for regenerating a particle filter assembly mounted in an exhaust gas stream of an internal combustion engine comprising the steps of positioning an electrically conductive filter having a mesh size sufficiently small to prevent the passage of carbonaceous particles above a predetermined size through the mesh in series with the exhaust gas stream from the engine, and electrically connecting an electric power source to said filter at spaced time intervals and for a sufficient time during each connection of the electric power to heat said filter to a temperature sufficient to oxidize at least a portion of the carbonaceous material in the filter to carbon dioxide. Optionally, the step of electrically connecting the electric power source to the filter comprises the step of sequentially electrically connecting the power source to different portions of the filter during a single or sequential regeneration cycles.

Optionally, a controller is implemented having incorporated an estimation tool to decide whether regeneration of said filter or parts of said filter will be conducted or not based on an overall efficiency of the vehicle.

Having described our invention, many modifications thereto will become apparent to those skilled in the art to which it pertains without deviation from the spirit of the invention as defined by the scope of the appended claims. 

1. A particle filter assembly adapted to be mounted in an exhaust gas stream of an internal combustion engine comprising: an electrically conductive filter having a mesh size sufficiently small to prevent the passage of carbonaceous particles above a predetermined size through the mesh, said filter being positioned in series with the exhaust gas stream from the engine, a source of electric power, a control circuit which electrically connects said electric power source to said filter at spaced time intervals and for a sufficient time during each connection of the electric power to heat said filter to a temperature sufficient to oxidize the carbonaceous material in at least a portion of the filter to carbon dioxide.
 2. The invention as defined in claim 1 wherein said filter comprises stainless steel.
 3. The invention as defined in claim 1 wherein said filter comprises copper.
 4. The invention as defined in claim 1 wherein said control circuit sequentially electrically connects the electric power source to different portions of the filter.
 5. The invention as defined in claim 1 wherein said control circuit is microprocessor based.
 6. In combination with a vehicle having an internal combustion engine with an exhaust gas stream, a particle filter assembly comprising: a filter having a mesh size sufficiently small to prevent the passage of carbonaceous particles above a predetermined size through the filter, said filter being positioned in series with the exhaust gas stream from the engine, a source of electric power which includes an electric generator mechanically coupled to a mechanical output from the internal combustion engine, said electric power source being electrically connected to at least one electrical system of the vehicle, a control circuit which electrically connects said electrical power source to said filter at spaced time intervals and for a sufficient time during each connection of the electric power to heat said filter to a temperature sufficient to oxidize the carbonaceous material in the filter to carbon dioxide.
 7. The invention as defined in claim 6 wherein said filter comprises stainless steel.
 8. The invention as defined in claim 6 wherein said filter comprises copper.
 9. The invention as defined in claim 6 wherein said control circuit electrically connects said electric power source to said filter whenever the electrical power output from said generator exceeds the electrical power needs of said at least one electrical system.
 10. The invention as defined in claim 6 wherein said vehicle is a train.
 11. The invention as defined in claim 6 wherein said control circuit electrically connects said electric power source to said filter when the vehicle is in a boost status.
 12. The invention as defined in claim 6 wherein said control circuit sequentially electrically connects the electric power source to different portions of the filter.
 13. The invention as defined in claim 6 wherein said control circuit is microprocessor based.
 14. The invention as defined in claim 6 wherein a controller is implemented having incorporated an estimation tool to decide whether regeneration of said filter or parts of said filter will be conducted or not based on an overall efficiency of the vehicle.
 15. A method for regenerating a particle filter assembly mounted in an exhaust gas stream of an internal combustion engine comprising the steps of: positioning an electrically conductive filter having a mesh size sufficiently small to prevent the passage of carbonaceous particles above a predetermined size through the mesh in series with the exhaust gas stream from the engine, electrically connecting an electric power source to said filter at spaced time intervals and for a sufficient time during each connection of the electric power to heat said filter to a temperature sufficient to oxidize at least a portion of the carbonaceous material in the filter to carbon dioxide.
 16. The method as defined in claim 15 and comprising the step of sequentially electrically connecting the power source to different portions of the filter.
 17. The method as defined in claim 15 wherein the step of sequentially electrically connecting the power source to different portions of the filter comprises the step of sequentially electrically connecting the power source to different portions of the filter during different regeneration cycles. 